THE ALCOHOL TEST IN/ RELATION TO MILK. 



17 



Table 13. — Effect of heat on the alcohol test with milk in which the positive test is due to 



rennet action. 



Milk heated 

 to— 



Alcohol test. 



75 per cent. 



68 per cent. 



Experi- 

 ment I. 



Experi- 

 ment II. 



Experi- 

 ment I. 



Experi- 

 ment II. 



"0. 



Not heated... 



40 



60 



+L 



+L 

 + L 



+ S 



+L 

 + L 

 + L 

 +L 

 +VS 



+L 

 +L 

 +L 

 +L 



+S 



+L 

 +L 

 +L 

 + L 

 +VS 



70 



80 



90 





Note. — Acidity of milk in experiment I, 1.82; in experiment II, 1.84. 

 1 See footnote under Table 1. 



The results which we have shown on the effect of rennet action in 

 relation to the alcohol test confirm the work of other investigators, 

 and it is evident that the rennet-forming group of bacteria in milk 

 can play an important part in the production of a positive alcohol test. 



INFLUENCE ON THE ALCOHOL TEST OF CARBON DIOXID LN MILE. 



There are probably numerous minor factors which influence the 

 alcohol test with market milk. While the two principal factors are 

 probably acidity and the effect of rennet action, it is believed by some 

 investigators that carbon dioxid plays a more or less important part. 

 Auzinger (2) found that milk one hour old which gave a positive 

 alcohol test gave a negative test after it had been held for 18 hours. 

 He believes that carbon dioxid might be partly responsible for such a 

 change. 



We have passed carbon-dioxid gas into milk many times and have 

 always been able to cause a positive alcohol test. In one experiment 

 carbon-dioxid gas was passed into milk until the acidity was 2.36 

 (titration in cold milk with phenolphthalein as an indicator), and a 

 positive alcohol test was obtained with 75 per cent and 68 per cent 

 alcohol. As is shown in Table 14, this milk was heated at different 

 temperatures up to 100° C. With the increase in temperature the 

 acidity was reduced, due probably to the expelling of the C0 2 . Barille 

 (4) has shown that carbon dioxid forms a very unstable compound, 

 which he calls carbono phosphate of calcium and is easily broken up 

 by heat. When the temperature reached 70° C, the alcohol test with 

 68 per cent alcohol was negative and the acidity had been reduced 

 from 2.36 to 2.05. At 90° C. the acidity was 1.91 and the alcohol 

 test was negative with 75 per cent alcohol. 



There can be no doubt as to the fact that carbon dioxid may cause 

 a positive alcohol test, provided there is a large enough amount in the 

 82832°— Bull. 202—15 3 



